Telecommunication operators today use a charging system to determine the charge to their subscribers which use their services, e.g., circuit switched voice, SMS, MMS and/or GPRS. The subscribers often have either a prepaid option or a postpaid option which they use to pay for a particular service. If a subscriber uses the postpaid option, s/he pays for a service after it has been used, e.g., once a month. If a subscriber uses the prepaid option, then s/he pays before the usage of a service. Both payment options can use real time charging also referred to as credit control, wherein the charging is executed during ongoing service delivery. The postpaid option also supports non-real time charging, wherein the charging executed after service delivery.
Therefore, during a charging session at least one calculation run based on service usage is performed by the charging system. E.g., the charging system determines the charge for a service according to the duration of the service, the time of service usage, use of a promotion campaigns etc.
As is explained in WO 2003/3032657, real time charging of service delivery relies on a reservation of funds corresponding to an invoked service in order for the invoked service to be allowed to execute. When the granted reservation of funds is used up by the service the service reports back, and its used funds are removed from an account and any excess amount of the reservation is put back on the account. If continued execution of the service is required a new reservation is made for the service.
However, in the known charging system there is no way to optimize the distribution of available funds between simultaneous services, services that are listed in one and the same request for reservation or parallel services not emanating from the same reservation request. Further there is no optimization with respect to different service types also referred to as unit types in the following, e.g., service usage time, total data volume, downlink data volume, uplink data volume, event like SMS or MMS, etc.